1. Field of the Invention
The present invention relates to a resource allocation method for a hybrid automatic repeat request (HARQ), and more particularly to a method for transferring only a difference between information capable of being recognized by a media access protocol (MAP) message received from a previous frame and a retransmitted sub-burst, resulting in the implementation of resource allocation.
2. Discussion of the Related Art
A data retransmission method of a transmission end or a reception end will hereinafter be described in detail. A wireless communication system provides a high-speed data service using a limited amount of resources. For this high-speed data service, an automatic repeat request (ARQ) capable of effectively employing resources is used. Namely, if data generated from the transmission end fails to be transferred to the reception end, the reception end requests retransmission of this failed data. In this case, an automatic repeat request (ARQ) scheme has been widely used to automatically retransmit data.
According to the ARQ scheme, after the reception end has received data from a transmission end, it transmits an acknowledgement (ACK) signal and/or a non-acknowledgement (NACK) signal to the transmission end, such that the reception end informs the transmission end whether or not the data has been correctly received. If the transmission end receives the NACK signal from the reception end, it determines the occurrence of an error in the data transferred to the reception end, such that it retransmits the data to the reception end. The ARQ scheme has three kinds of ARQ schemes, i.e., a Stop-And-Wait (SAW) ARQ scheme, a Go-Back-N (GBN) ARQ scheme, and a Selective-Repeat (SR) ARQ scheme.
According to the SAW ARQ scheme, the transmission end transmits original data to the reception end, and waits to receive the ACK or NACK signal from the reception end. Upon receiving the ACK signal from the reception end, the transmission end transmits new data corresponding to the next data. Otherwise, if the transmission end receives the NACK signal from the reception end, it retransmits the original data instead of the next data. In other words, the SAW ARQ scheme transmits only one frame at one time. After the transmission end recognizes that the frame has been successfully transmitted to the reception end, it transmits the next frame.
According to the GBN ARQ scheme, it enables the transmission end to continuously transmit data, irrespective of a response message (e.g., ACK or NACK message) from the reception end. If the reception end does not receive data of a specific frame while receiving data from the transmission end, it is unable to transmit the ACK signal of the specific frame to the transmission end. So, the transmission end does not receive the ACK signal of the specific frame from the reception end, such that it retransmits data from the specific frame.
According to the SR ARQ scheme, if the transmission end receives the NACK signal from the reception end while continuously transmitting data to the reception end, it retransmits only specific data encountering the NACK signal to the reception end. If the transmission end receives the NACK signal from the reception end, it retransmits only data of a frame denoted by the NACK signal to the reception end, such that it can successfully transmit all of data to the reception end. The SR ARQ scheme must assign unique sequence numbers to individual frames, and must manage the individual frames. As a result, it is difficult to implement the SR ARQ scheme.
According to a scheme for configuring data in the form of a packet and transmitting this packet-formatted data, a higher data rate is needed for this packet-based data transmission scheme. In order to prevent any errors from being generated in a high-speed transmission environment, a new coding rate or a new modulation method is being intensively developed and applied to a communication system. There is also proposed a hybrid ARQ (HARQ) scheme suitable for the high-speed transmission environment.
According to the ARQ scheme, if data is faulty or erroneous data, the ARQ scheme discards this data. However, according to the HARQ scheme, the reception end stores the erroneous data in a buffer, combines the stored data with the retransmitted data, and applies a forward error correction (FEC) scheme to the combined resultant data. In other words, the HARQ scheme is considered that the FEC scheme is combined with the ARQ scheme. In this case, the HARQ scheme can be classified into four types, i.e., the following first to fourth types.
The first type of the HARQ scheme is as follows. According to the first type of the HARQ scheme, the reception end always checks the presence or absence of an error detection code in data, and primarily applies the FEC scheme to the checked result. If a packet received in the reception end has the remaining errors, the reception end requests the transmission end to retransmit the original data having no errors. The reception end discards the erroneous packet, the transmission end applies the same FEC code as that of the discarded packet to another packet to be retransmitted, and transmits the resultant packet.
The second type of the HARQ scheme is as follows. This second type of the HARQ scheme may also be called an incremental redundancy (IR) ARQ scheme. According to this IR ARQ scheme, the reception end does not discard a first transmission packet, stores the first transmission packet in a buffer, and combines the stored first transmission packet with retransmitted redundancy bits. During the data retransmission time, the transmission end retransmits only parity bits other than data bits. The parity bits retransmitted by the transmission end are changed to others whenever data is retransmitted.
The third type of the HARQ scheme is as follows. The third type of the HARQ scheme is a specific case of the above-mentioned second type. Each packet can be self-decodable. If the transmission end retransmits data, it configures a packet including both the erroneous part and the data part, and then retransmits the configured packet. This third type of the HARQ scheme can perform the decoding process more correctly than the above second type of the HARQ scheme, whereas it has a coding gain less than that of the second type of the HARQ scheme.
The fourth type of the HARQ scheme is as follows. According to the fourth type of the HARQ scheme, a specific function is added to the first type of the HARQ scheme. In more detail, this specific function enables the reception end to store first reception data, and allows this first reception data to be combined with retransmission data. This fourth type of the HARQ scheme is called a Metric Combining (MC) scheme or a Chase Combining (CC) scheme. The above fourth type of the HARQ scheme is advantageous to a Signal to Interference Noise Ratio (SINR) aspect, and always uses the same parity bits of retransmission data.
However, in order to allow a current system to support the HARQ scheme, a base station transmits subburst-associated information to a mobile station via a MAP message. In this case, if there are a large amount of HARQ traffic, the base station must continuously transmit the MAP message, such that an amount of overhead of the MAP message may unavoidably increase.